Roller bearing cage

ABSTRACT

A roller bearing cage is disclosed in which a pair of semicircular cage halves is assembled with their mating ends thereof coming into abutment against each other. The mating ends are chamfered off to stave off bearing failure resulting from any deformation that might occur at the areas nearby the mating ends owing to large centrifugal force imposed by high-speed engines. The roller bearing cage may be completed by only joining together the semicircular cage halves with their diametral mating ends coming into engagement with one another. Each of the semicircular cage halves is composed of axially opposing semicircular rims and cage bars interposed between the rims, thus helping ensure stiffness with even weighing less. The chamfering operation is done to make even any outer peripheral areas nearby the mating ends, preparatory to cutoff operation to split a cylindrical cage stock into two halves. This helps the process management of material-removal work to make the chamfered even areas.

The present application is a Division of prior application Ser. No.10/028,829, filed Dec. 28, 2001 now U.S. Pat. No. 6,666,584.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a roller bearing cage applied to, forexample a lower, larger end called a rod “big end” of a connecting rodin an engine and more particularly to a roller bearing cage suitable foruse in a split shell roller bearing designed to fit around a crankshaftin which crankpins are made integrally with crank webs.

2. Description of the Prior Art

As the modern engines are needed to get further higher in horsepower,the crankshaft for the powerful engines has to be made so as to stand upto further high-speed revolution. To cope with this, the crankpins aremade integral with the crank webs to enhance the rigidity or stiffnessof the crankshaft. Split shell roller bearings, because of the integralconstruction of the crankpin with the associated crank webs, areinevitably required at the rod big-ends of the connecting rods andcorrespondingly the cage is also needed to be made in any split type.High-compression, high-speed engines, moreover, impose very harshconditions to the bearings.

An example of conventional bearing cages is disclosed in PublishedUnexamined Patent Application in Japan No.H08-219 149. The prior bearingcage is made in a configuration resembling any gate in cross section andenvisaged to carry effectively the loads imposed by modern high-speedengines. To this end, the cage is made on the outside periphery thereofwith the retaining projections to keep the rollers against their escapeout of the cage.

Another example of the bearing cage having a gate-like configuration incross section is disclosed in Published Unexamined Utility ModelApplication in Japan No.H01-168 014. The prior bearing cage is alsodirected to keep the rollers against their escape out of the cage,thereby carrying well the heavy loads imposed by high-speed engines. Tothis end, the bearing cage, as illustrated in FIG. 1 of the abovecitation, has a partition separating two adjacent pockets, the thin areaof which is made with projections that extend inside the pocketsslightly beyond the flanks of the thickened areas to serve for keepingthe rollers against their radially outward escape out of the cage.

Published Unexamined Patent Application in Japan No. 2 000-240 660discloses a roller bearing retainer split into two haves, which isfavorable for the crankshaft having crankpins formed integrally with thecrank webs. The prior roller bearing retainer is designed in such a wayreduced in an outside diameter thereof as nearing the diametral opposingabutment ends of the retainer halves to be made in a somewhat ovalshape. The construction recited above is envisaged to keep the retaineragainst any unfavorable deformation where the retainer may get bulgedradially at the diametral opposing abutment ends of the retainer halves.

Another split type of the roller bearing cage is disclosed in PublishedUnexamined Utility Model Application in Japan No.H06-6 746, in which anannular cage of true round is split into two halves along a diametralplane lying on the circumferential midway points of any two diametralopposing cage bars. The cage halves are covered with any coatingmaterial of a preselected thickness at their at least any one side ofsplit ends that come into circumferential abutment against one another.

Moreover, Published Unexamined Patent Application in Japan No.H09-72 332discloses a connecting-rod bearing construction for marine engines, inwhich a needle bearing for a rod big-end is composed of a pair ofsemicircular cage halves, which come into abutment against each other toform a completely circular cage.

None of the prior bearing cages of split type recited earlier,nevertheless, succeeds in overcoming a major problem in which the splitcage is much subject to deformation of bulging radially outwardly at theabutment ends of the cage halves owing to large centrifugal force takingplace when the bearing revolves at high speed. This will cause thebearing to seat improperly in the bore surface in the rod big-end of theconnecting rod, thus resulting in bearing failure such as lack oflubricating oil, seizing or binding between the bearing and theconnecting rod, and so on.

An example of the prior bearing cages of split type envisaged to resolvethe problem stated just above is illustrated in FIG. 11. The priorsplit-type bearing cage 40 is generally composed of a pair ofsemicircular cage halves 41, which are chamfered at a corner 39 wherethe abutment ends of the semicircular cage halves 41 merge with theoutside peripheral surface of the cage. Rollers 43 are installed inpockets arranged circumferentially of the cage.

With the prior bearing cages of split type constructed as statedearlier, chamfering work on the corners is done to the semicircular cagehalves 41, separately, which have been previously prepared by splittinga cylindrical cage stock. This chamfering procedure is much unfavorablefor precision control of the chamfered area 39 in size. Thus, not onlythe chamfered area 39 get scattered in their sizes, but also an edgewhere the chamfered area merges with the associated outside periphery 42of the cage will tend to be made much sharp. The tendency will cause anylikelihood of raising the lack of lubricating oil, the seizing ofbearing and so on at the abutment ends 38 and any area nearby the ends.With the prior bearing cages of split type, moreover, as the cylindricalcage is usually subject to heat treatment in preparatory to cutting intosemicircular cage halves 41, the resulting cage halves can't helpspreading somewhat radially outwardly at the time of cutting. This alsomakes it tough to prepare the chambered area at the corner with highprecision.

SUMMARY OF THE INVENTION

The present invention has for its primary object to resolve the majorproblem as stated earlier, and to provide a roller bearing cage of splittype, which serves useful functions for bearings in, for example aconnecting rod in high-compression, high-speed engine and moreparticularly to a roller bearing cage that is easy in fabricationthereof and precision control of a chamfered area, and further muchfavorable for the bearings, which are needed to stand up to the harshconditions imposed by high-compression, high-speed engines.

The present invention is concerned with a roller bearing cage in which acylindrical cage is split along any diametral plane thereof into a pairof two semicircular cage halves that are arranged in opposition to eachother with their mating ends coming into abutment against each other:comprising that the semicircular cage halves are each composed ofsemicircular rims arranged in a way spaced axially apart from each otherand extended circumferentially in parallel with each other, and cagebars positioned between the semicircular rims at regular intervalsaround curved surfaces of the rims and made integrally with the rims toform a pocket between any two adjacent cage bars, in which a roller isaccommodated for rotation; the semicircular cage halves are chamferedoff at any outer peripheral areas nearby the mating ends thereby to formchamfered even areas; and the chamfering operation is done preparatoryto cutting off the cylindrical cage into two semicircular cage halves.

In one aspect of the present invention there is disclosed a rollerbearing cage in which the chamfered even areas on the outer peripheralareas are roughly normal to the mating ends of the semicircular cagehalves and also lying on planes that extend in parallel with each otherin diametral opposition.

In another aspect of the present invention, there is disclosed a rollerbearing cage in which the cage bar having the mating end thereon isroughly equal in circumferential width with other cage bar. Moreover,the cage bars are arranged with their outside surfaces being in flushrelation with the outside peripheries of the rims.

In another aspect of the present invention there is disclosed a rollerbearing cage in which the cage bar has an inside surface that is sunk atan axial middle area thereof to form a recess extending in depthradially outwardly beyond a diameter across pitch circle on the rollersand in axial length shorter than the pocket, so that the cage bar ismade slender at the middle area thereof on account of the recess, withleaving axially opposing ends thereof thick, and circumferentiallyopposing cheeks of the thick ends provide guide surfaces on which theroller rolls.

In another aspect of the present invention there is disclosed a rollerbearing cage in which on the thick ends of the cage bar there areprovided outside retainer lugs that jut into the pocket to keep theroller against outward escape out of the associated pocket and insideretainer lugs that also jut into the pocket to keep the roller againstinward escape out of the associated pocket.

In another aspect of the present invention there is disclosed a rollerbearing cage in which an annular corner where the inside peripheralsurface and any one end of the axially opposing end surfaces of thesemicircular rims merge with each other is chamfered off into a depthreaching two-thirds an axial thickness of the associated rim to form aslant annular surface, which slopes to a plane normal to an axialdirection of the rim, with an angle less than 45 deg.

In another aspect of the present invention there is disclosed a rollerbearing cage in which the edge where the outer periphery of thesemicircular rim and the cage bar merges with the associated mating endis chamfered off. The chamfering operation on the areas nearby themating ends, since done prior to cutting off the cylindrical cage intotwo halves, allows preparing the chamfered even areas that extendequally over both the semicircular cage halves. Chamfering the edgesnearby the mating ends, thus, is beneficial in preventing the boreinside surface in the rod end of the connecting rod against theinterference with such edges during rotation of the roller bearing cage,thereby making sure of smooth revolution of the roller bearing cage.

In another aspect of the present invention there is disclosed a rollerbearing cage in which a corner where the axial end surface of thesemicircular rim merges with the outside periphery of the semicircularrim is slightly rounded.

In a further another aspect of the present invention there is discloseda roller bearing cage wherein a cylindrical cage is composed of a pairof annular rims arranged in a way spaced axially apart from each otherand extended circumferentially in parallel with each other, and cagebars positioned between the annular rims at regular intervals aroundcurved surfaces of the rims and made integrally with the rims to form apocket between any two adjacent cage bars, in which a roller isaccommodated for rotation; the cage bars are arranged with their outsidesurfaces being in flush relation with the outside peripheries of therims; the cage bar has an inside surface that is sunk at an axial middlearea thereof to form a recess extending in depth radially outwardlybeyond a diameter across pitch circle on the rollers and in axial lengthshorter than the pocket, so that the cage bar is made slender at themiddle area thereof on account of the recess, with leaving axiallyopposing ends thereof thick, and circumferentially opposing cheeks ofthe thick ends provide guide surfaces on which the roller rolls, andfurther wherein on the thick ends of the cage bar there are providedoutside retainer lugs that jut into the pocket to keep the rolleragainst outward escape out of the associated pocket and inside retainerlugs that also jut into the pocket to keep the roller against inwardescape out of the associated pocket.

In another aspect of the present invention there is disclosed a rollerbearing cage in which an annular corner where the inside peripheralsurface and any one end of the axially opposing end surfaces of theannular rims merge with each other is chamfered off into a depthreaching two-thirds an axial thickness of the associated rim to form aslant annular surface, which slopes to a plane normal to an axialdirection of the rim, with an angle less than 45 deg. Moreover, a cornerwhere the axial end surface of the annular rim merges with the outsideperiphery of the annular rim is slightly rounded.

In another aspect of the present invention there is disclosed a rollerbearing cage in which the slender area of the cage bar is defined in amanner having an inside surface of an axial length extending over arange of from 50% to 80% of an axial length of the pocket.

In another aspect of the present invention there is disclosed a rollerbearing cage in which a slant surface connecting the slender area andany one of the thick ends is set to slope to a plane normal to theslender area, with an angle less than 45 deg.

In another aspect of the present invention there is disclosed a rollerbearing cage in which the outside retainer lugs formed on the thick endsof the cage bar are designed in such a manner that their radiallyoutside tops are held in flush relation with the outer periphery of thecage bar.

In another aspect of the present invention there is disclosed a rollerbearing cage in which an axially middle area of the cage bar is reducedsidewise on circumferentially opposing cheeks thereof to enlargewidthwise the pocket.

In a further another aspect of the present invention there is discloseda roller bearing cage in which the cage is made in an outside guideconstruction in which the outside periphery thereof is guided along abore surface in a rod end of a connecting rod.

With the roller bearing cage of split type constructed according to thepresent invention, the chamfering operation on the areas nearby themating ends of the two cage halves is done preparatory to cutting offthe cylindrical cage stock into two cage halves. The machining processstated earlier is beneficial in keeping the resulting chamfered areasagainst getting scattered in their sizes. Thus, this renders thehigh-precision measurement of the chamfered areas easier, and makingsure of process management of material-removal work to make thechamfered areas into a preselected shape. The chamfering operation doneon the cage stock prior to the cutoff process, moreover, makes itpossible to finish the chamfered areas on the outside periphery withhigh accuracy. Besides, the chamfered areas are made substantially evenand therefore it will be easy to machine any bound between the chamferedeven area and the curved surfaces around the roller bearing cage into asmoothly round area. Machining the bound where the chamfered even areamerges with the curved surface of the outer periphery into any smoothand round surface serves well to bypass any issue that the outerperiphery of the cage might otherwise come into unevenly forced seat atthe bounds thereof against the bore surface in the rod big-end of theconnecting rod, along which the rollers roll. Thus, the split cage ofthe present invention is constructed to carry effectively the loadsimposed by modern high-speed engines, with no bearing failure.

Cutting off the cylindrical cage stock into two cage halves is doneusing a wire-electric discharge machining in which the kerf or width ofcut is small with a consequently less removal in material than othertraditional cutoff machining operations. Thus, the wire-electricdischarge machining is in favor of splitting accurately the cage stockinto two semicircular cage halves. Chamfering operation using thewire-electrode is preferable for Simplifying the machining operations,with even making high-accuracy machining possible.

The roller bearing cage constructed as stated earlier weighs less,making the outer periphery of the cage larger in size, and also is madesmall in surface-to-surface contact stress that might take place betweenthe bore surface in the rod big-end of the connecting rod and the outerperiphery 22 of the roller bearing cage 1, thus, favorable for carryingthe loads imposed by the high-speed revolution, with no occurrence ofbearing failure such as the lack of lubricating oil, the seizing ofbearing and so on.

Other objects and features of the present invention will be moreapparent to those skilled in the art on consideration of theaccompanying drawings and following specification wherein are disclosedpreferred embodiments of the invention with the understanding that suchvariations, modifications and elimination of parts may be made thereinas fall within the scope of the appended claims without departing fromthe spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front elevation showing a preferred embodiment of a rollerbearing cage according to the present invention:

FIG. 2 is a traverse cross-section illustrating any one of semicircularcage halves, taken on the plane perpendicular to an axial direction ofthe roller bearing cage shown in FIG. 1:

FIG. 3 is a view, partially broken away, of the semicircular cage halfof FIG. 2 taken along the plane I—I as seen looking into the insidethereof in the direction of an arrow E of that figure:

FIG. 4 is a fragmentary plan view of the semicircular cage half of FIG.2 as seen in the direction of an arrow F of that figure:

FIG. 5 is an enlarged fragmentary view illustrating a chamfered areaencircled with character G in FIG. 1:

FIG. 6 is a traverse cross-section illustrating a cylindrical cage stocktaken on the plane perpendicular to an axial direction thereof, which isshown preparatory to splitting into two semicircular cage halves toproduce the roller bearing cage of the present invention:

FIG. 7 is an enlarged fragmentary view illustrating a chamfered areaencircled with character H in FIG. 6:

FIG. 8 is a schematic illustration explanatory of a chamfered area on anoutside periphery of the roller bearing cage according to the presentinvention in comparison with cage stock preparatory of chamfering:

FIG. 9 is an enlarged fragmentary view illustrating in detail a partencircled with character H in FIG. 3:

FIG. 10 is perspective view illustrating another embodiment of theroller bearing cage according to the present invention, which is aunitary type holding therein more than one roller: and

FIG. 11 is a front elevation of a prior roller bearing cage to explainchamfered areas worked on the semicircular cage halves.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now in detail to FIGS. 1 to 9, a preferred embodiment of aroller bearing cage according to the present invention will be explainedbelow.

With the embodiment constructed as stated later, a roller bearing cage 1is of the split type that mainly comprises a pair of semicircular cagehalves 2 and has features of configuration, especially, at abutment ends8 and areas nearby the ends. The roller bearing cage 1 is made of acylindrical cage stock 10, which is split into two cage halves bycutting-off work to form a pair of semicircular cage halves 2. Thecylindrical cage stock 10, as illustrated in FIGS. 6 and 7, is cut offat diametral opposing chamfered areas 9, in more detail, along adiametral plane 11 lying on circumferential midway points of the twodiametral opposing cage bars 4 each of which is twice any other cage bar4 in circumferential width. Each of the paired semicircular cage halves2 fits into a bore in the rod end of the connecting rod in such a waycoming into mutual abutment against the counterpart thereof at theirmating ends 8 to form a cylinder thereby to complete the roller bearingcage 1.

The semicircular cage halves 2 are each composed of a pair ofsemicircular rims 3 spaced apart from each other in a way extendingcircumferentially in parallel with each other to keep a preselectedaxial interval between them, and cage bars 4 positioned at regularintervals around the curved surface of the rims 3 and connectedintegrally to the rims 3 to form a window or pocket 6 between any twoadjacent cage bars 4, in which a roller 7 such as a needle roller islaid. At mating ends 8 of the semicircular cage halves 2, there areshown both the rims 3 and the cage bar 4, which are partially shaveddown at an outer periphery 22 of the associated semicircular cage half 2in a manner providing a chamfered even area 9 at a radially outsidecorner 5 and an area nearby the corner 5 of any mating end 8 of thesemicircular cage half 2. Moreover, it is preferable to grind away anedge 23, where the radially outside corner 5 merges with the associatedmating end 8, into a rounded edge 23C.

Chamfering work at the radially outside corner 5 nearby the mating end 8to provide the chamfered even area 9 there is performed on thecylindrical cage stock 10 shown in FIG. 6, preparatory to splitting thestock 10 into two semicircular cage halves 2, by cutting away a desiredvolume of material from the outside periphery 22 of the cage stock 10 ina way making the chamfered even area 9 that extends axially of the cagestock 10 over a circumferential width in sidewise symmetry with respectto a diametral plane 11 lying on a cutoff line along which the cagestock 10 will be split into two cage halves 2. The volume 12 removedfrom the outside periphery 22 of the cage stock 10 is determined inlight of an amount of deformation that might occur in the roller bearingsplit-cage 1, a centrifugal force that might be exerted due to anyhigh-speed revolution on the roller bearing split-cage 1 fit in the rodend of the connecting rod, and so on. Making the chamfered even area 9on the cylindrical cage stock 10 before split-up process makes itpossible to form two chamfered even areas 9 on the outside periphery ofthe cage stock 10 in accurately diametral opposition to one another.This renders the high-precision measurement of the chamfered area 9easier, thus helping the process management of material-removal work tomake the chamfered even areas 9 into a preselected shape. The chamferingoperation done on the cage stock prior to the cutoff process, moreover,makes it possible to finish the chamfered even areas 9 on the outsideperiphery 22 with high accuracy. Besides, any bound between thechamfered even area 9 and the curved surfaces extending over the rim 3and the cage bar 4 is preferably made into a smoothly round area.

As only two diametrically opposing cage bars 4 where the cylindricalcage stock 10 will be cut off into two cage halves 2 has acircumferential width twice other cage bars 4, any circumferentiallyterminal cage bar 4 with the mating end 8 of the semicircular cage half2 is roughly equal in circumferential width with other cage bars 4. Withthe semicircular cage halves 2 constructed as stated just above, sincethe mating end 8 is provided by the combination of the semicircular rims3 and the terminal cage bar 4 that is not less in sidewise width thanother cage bars 4, there is no practical issue in mechanical strength.Cutting off the cylindrical cage stock 10 is done using for example awire-electric discharge machining. As modern advanced wire-electricdischarge processors use a thin wire electrode as small as, for example0.1 mm in diameter, the kerf or width of cut is small with aconsequently less removal in material than other traditional cutoffmachining operations. Thus, the wire-electric discharge machining is infavor of splitting accurately the cage stock 10 into two semicircularcage halves 2.

The shaded portions on the cage stock 10 in FIG. 8(III) are firstchamfered off using the wire-electric discharge machining to provide thechamfered even areas 9, which are in diametral opposition to each other.Then, the cage stock 10 is split into two semicircular cage halves 2along the axial cutoff plane 11 in FIG. 8(IV) by the action of thewire-electric discharge machining using a thin wire. At the same time,grinding away the edge 23 into the rounded edge 23C by the use of thethin wire-electrode is preferable for simplifying the machiningoperations, with even making high-accuracy machining possible. It willbe appreciated that any material removal operations other than thewire-electric discharge machining may be used for the chamfering workson the outer periphery of the cage stock 10 and the edges 23 of thesemicircular cage halves 2.

As seen from FIG. 5 in which a chamfered area encircled with character Gin FIG. 1 is shown as being enlarged, the chamfered even area 9 may befinished with accuracy by the removal of a specified portion at 12 fromthe outer periphery 22 of the cage stock 10 in such a way preparing asubstantially even surface. Moreover, while a bound 9C where thechamfered even area 9 merges with the curved surface of the outerperiphery 22 is made into any smooth and round surfaces, the edge 23where the chamfered area 9 meets the mating end 8 is machined to end ina gently round corner 23C rather than in a sharp corner. The split cage1 machined as stated earlier may be free from any issue that the outerperiphery 22 of the cage 1 might come into unevenly forced seat at thebounds 9C thereof against the bore surface in the rod big-end, alongwhich the balls roll. Thus, the split cage of the present invention isconstructed to carry effectively the loads imposed by modern high-speedengines, with no bearing failure such as lack of lubricating oil at themating ends 8 and any area nearby the ends.

The cage bar 4, as shown in FIG. 3, is arranged in a way that itsradially outside surface 22P is flush with the outer periphery 22 of thesemicircular rim 3, so that the cage bar is held in a flush relationwith the outer periphery 22 of the semicircular rim 3 over the overalllength thereof. The cage bar 4 also has a radially inside surface 24that is sunk at an axial middle area thereof to form a recess 19extending in depth radially outwardly beyond a diameter D of pitchcircle of the successive rollers 7, or a distance D across pitch circleon the diametrally opposite rollers 7 and in axial length shorter thanthe associated pocket 6. Provision of the recess 19 on the insidesurface 24 of the cage bar 4, therefore, results in making the cage bar4 slender at the middle area 14 thereof, with leaving the axiallyopposing ends 13 thereof thick. Circumferentially opposing cheeks of thethick ends 13 define the window or pocket 6 and at the same time provideguide surfaces 18 on which the roller 7 rolls.

On the thick ends 13 of the cage bar 4 there are provided outsideretainer lugs 15 that jut into the pocket 6 to keep the roller 7 againstoutward escape out of the associated pocket 6 and inside retainer lugs16 that also jut into the pocket 6 to keep the roller 7 against inwardescape out of the associated pocket 6. The inside retainer lugs 16 aremade by coining grooves 28 on the inside circumferential surface 24 ofthe cage bar 4 with the use of, for example knurling tools and so on toextrude the material into the associated pocket 6. Moreover, the outsideretainer lugs 15 formed on the thick ends 13 of the cage bar 4 aredesigned in such a manner that their radially outside tops are held inflush relation with the outer periphery 22 of the cage bar 4.

As shown in FIGS. 3 and 9, the slender area 14 of the cage bar 4 isdefined in a manner having an inside surface 24T of an axial length Bjextending over a range of from 50% to 80%, preferably roughly 60% asillustrated here, of an axial length Bp of the pocket 6. On the insideperipheral surface 24 of the cage, a slant surface 20 connecting theslender area 14 and any one of the thick ends 13 is set to slope to aplane normal to the slender area 14, with an angle (θ₂/2) less than 45deg. Preferably, the angle (θ₂/2) is set at 30 deg as illustrated here.An annular corner where the inside peripheral surface 24 merges with anyone end of the axially opposing end surfaces 25 of the semicircular rims3 is chamfered off into a depth reaching two-thirds the axial thicknessof the associated rim 3 to form a slant annular surface 21, which slopesto a plane normal to the axial direction of the rim 3, with an angle θ₁less than 45 deg. That is to say, the chamfered slant surface 21 on thesemicircular rim 3 starts at an annular line on the inside periphery ofthe semicircular rim 3, which is spaced apart from an axially inside endplane perpendicular to the axial direction by two-thirds the axialdistance on the of the semicircular rim 3. The corner 23 where the endsurface normal to the axial direction merges with the outside periphery22 of the semicircular rim 3 is slightly rounded. Besides, it is to benoted that the corner 23 where the end surface normal to the axialdirection merges with the outside periphery 22 of the semicircular rim 3should be rounded to such an extent that there is no occurrence ofinterference or engagement with an corner R of the crankpin integralwith the crankshaft, which will fit over the rounded corner 23.

Moreover, an axially middle area of the cage bar 4 is reduced sidewiseon circumferentially opposing cheeks thereof to enlarge at 17 widthwisethe pocket 6, thus allowing lubricating oil to flow through there. Thisconstruction contributes to making the lubricating oil easier to flowaround the rollers. An annular corner 26 where the axial end surface 25merges with the outside periphery 22 of the semicircular rim 3 isslightly rounded.

A pair of semicircular cage halves 2 is constituted with the cage bars 4and semicircular rims 3, which are constructed as stated just above.Only assembling the semicircular cage halves 2, with the mating ends 8thereof coming into abutment against their counterparts may provide theroller bearing cage 1, which weighs less and also makes the outerperiphery 22 of the cage 1 larger in size. The roller bearing cage 1completed as stated earlier is made small in surface-to-surface contactstress that might take place between the bore surface in the rod big-endof the connecting rod and the outer periphery 22 of the roller bearingcage 1 owing to the centrifugal force caused by the high-speedrevolution, thus, favorable for carrying the loads imposed by thehigh-speed revolution, with no occurrence of bearing failure such as thelack of lubricating oil, the seizing of bearing and so on. The rollers 7are each allowed to roll certainly with less skew on account of theassociated guide surfaces 18 made on the circumferentially opposingcheeks of the thick ends 13. In addition, as the thick ends 13 of thecage bar 4 are provided with the outside and inside retainer lugs 13,15, the rollers 7 are kept against direct contact with the cage barseven if the guide surfaces 18 are somewhat subject to wear. There is nopossibility of interference with the retainer lugs 15, 16. The rollers7, as held against escape out of the roller bearing cage 1, may behandled or treated with ease despite the cage 1 being split into pairedsemicircular cage halves 2.

The roller bearing cage constructed as stated earlier weighs less, witheven making sure of the guide surface that rivals the prior roller guidesurface. The roller bearing cage of the present invention, moreover, isso constructed as to help ensure stiffness in the semicircular rim 3,especially increase in modulus of longitudinal section, and also makethe outer periphery of the roller bearing cage 1 increased in area.Thus, the present invention provides the roller bearing cage that cancarry the loads imposed by high-compression, high-speed engines, despitebeing split into two cage halves.

The roller bearing cage 1 constructed as stated earlier will be producedaccording to the following processing steps:

1. Any metal stock such as tubular member and so on is made into apreselected configuration such as a cylindrical member and so on byturning operation;

2. The resulting cylindrical member is made with pockets 7 by pressingoperation;

3. The cylindrical member is then made with the outside and insideretainer lugs by coining operation;

4. The cylindrical member is subjected to grinding operation on theaxially opposing end surfaces thereof to have a preselected axiallength;

5. The cylindrical member is roughly ground around the outer peripherythereof;

6. The ground cylindrical member is subjected to heat-treatment;

7. The cylindrical member is finished around the outer periphery thereofby grinding operation;

8. The cylindrical member is first chamfered off at specified areas onthe outer periphery thereof, where the cylindrical member will be splitinto two halves, and then separated into the two halves by cutoffoperation with wire-electric discharge machining to make a pair ofsemicircular cage halves 2;

9. The split two halves are trimmed to remove any irregular edge causedby the wire-electric discharge machining operation;

10. The semicircular cage halves 2 are subjected to surface treatmentsby plating the whole surfaces of the semicircular cage halves 2; and

11. Rollers 7 are each fit in the associated pocket 6 from the outsideof the semicircular cage halves 2 in a snapping way deformingelastically the outside retainer lugs.

Finally referring to FIG. 10, there is shown another embodiment of theroller bearing cage according to the present invention. A roller bearingcage 30 is of unitary construction in return for the split cage composedof a pair of semicircular cage halves 2. The roller bearing cage 30 istruly identical with the roller bearing split-cage 1 stated earlier inconfigurations of the cage bars 4 and the rims 27, except that the rims27 are not split into two halves so that they don't have the mating ends8, which have been prepared on the diametrally opposing ends of thesemicircular cage halves 2 in the first embodiment stated earlier. Theroller bearing cage 30 according to the second embodiment, as with theroller bearing split-cage 1 according to the first embodiment statedearlier, also has the performance favorable for the high-speed engines.

While the present invention has been described in its preferredembodiments, it is to be understood that the words which have been usedare words of description rather than limitation and that changes withinthe purview of the appended claims may be made without departing fromthe true scope and spirit of the invention in its broader aspect.

1. A roller bearing cage wherein a cylindrical cage is composed of apair of annular rims arranged in a way spaced axially apart from eachother and extended circumferentially in parallel with each other, andcage bars positioned between the annular rims at regular intervalsaround curved surfaces of the rims and made integrally with the rims toform a pocket between any two adjacent cage bars to accommodate a rollerfor rotation; the cage bars are arranged with their outside surfacesbeing in flush with the outside peripheries of the rims across anoverall length of the cage; the cage bar has an inside surface that issunk at an axial middle area thereof to form a recess extending in depthradially outwardly beyond a diameter across pitch circle on the rollersand in axial length shorter than the pocket, so that the cage bar ismade slender at the middle area thereof on account of the recess, withleaving axially opposing ends thereof thick, the axially opposing thickends are provided on circumferentially opposing cheeks thereof withguide surfaces on which the roller rolls, and further wherein on thethick ends of the cage bar there are provided outside retainer lugs thatjut into the pocket to keep the roller against outward escape out of theassociated pocket and inside retainer lugs that also jut into the pocketto keep the roller against inward escape out of the associated pocket,wherein an annular corner where the inside peripheral surface and anyone end of the axially opposing end surfaces of the annular rims mergewith each other is chamfered off into a depth reaching two thirds athickness on the end surface of the associated annular rim from theinside peripheral surface of the annular rim, which slopes to a planenormal to an axial direction of the rim, with an angle less than 45 deg,wherein a corner where the axial end surface of the annular rim mergeswith the outside periphery of the annular rim is slightly rounded,wherein the slender area of the cage bar is defined in a manner havingan inside surface of an axial length extending over a range of from 50%to 80% of an axial length of the pocket, and wherein a slant surfaceconnecting the slender area and any one of the thick ends is set toslope to a plane normal to the slender area, with an angle less than 45deg.
 2. A roller bearing cage constructed as defined in claim 1, whereinthe outside retainer lugs formed on the thick ends of the cage bar aredesigned in such a manner that their radially outside tops are held inflush relation with the outer periphery of the cage bar.
 3. A rollerbearing cage constructed as defined in claim 1, wherein the axiallymiddle area of the cage bar is reduced sidewise on circumferentiallyopposing cheeks thereof to enlarge widthwise the pocket.